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Seasonal ratings offer accuracy and opportunity

A draft Energy using Product (EuP) Directive from the European Commission is expected to come into force in 2013, meaning the performance of AC equipment will be calculated according to its seasonal efficiency rating over the entire year - and this will eventually appear on a new energy label.

Once the new regulations come into force, all new units after that date that are unable to meet EuP requirements will be banned.

Up until now, the performance of an air conditioning system has been expressed in terms of nominal performance, but this approach can hide significant differences between rated and actual performance.

This is because nominal performance is calculated at specific temperatures so unit performance is optimised, even though these exact conditions occur fairly rarely.

As a result, this does not reflect the real efficiency of a system over the whole year.

The seasonal efficiency rating offers a more accurate picture of a system’s performance, because it takes into account multiple cooling and heating temperatures, which are much closer to the reality of fluctuating temperatures over the year.

This also demonstrates the unit operation at partial load instead of just at full capacity, where the benefits of inverter technology are not visible.

What’s more, the seasonal efficiency rating shows users the power consumed by equipment in auxiliary mode, which can consume an extra 136 kWh of energy per year, so gives users a better idea of anticipated real-life performance.

While there’s a tendency to view this legislation with foreboding, these new requirements also provide an opportunity to reduce energy usage and costs.

Because the seasonal energy efficiency ratio (SEER) is a much more accurate measure of an air conditioning system’s efficiency than the more traditional EER, increases in efficiency can be demonstrated and more accurate simulations provided.

The technology already exists to fulfil these legislative requirements and deliver improved energy efficiencies.

If legislation continues to drive innovation in this way, motivating manufacturers to strive for greater energy efficiencies, this surely has to be a welcome impetus.

John Durbin is engineering department manager for Daikin UK